Fig. 1

a Circular map of the chromosome of E. coli O157:H7 strain NADC 6564 generated from its annotated sequence. The map was constructed by downloading the chromosomal sequence into the Blast Ring Image Generator. The legend on the top right corner shows rings representing GC content, GC skew, inserted phage or phage-like elements (red), and ORFs on – (orange) and + (blue) DNA strands. b Comparing chromosomal organization of E. coli O157:H7 strain NADC 6564 to published chromosomal sequences of other E. coli O157:H7 strains (NADC 6565, EDL933, Sakai, FRIK2533, TW14359), non-O157 strains (O111 and O26) and a non-pathogenic E. coli K12 strain MG1655. Linear Conservative Blocks or LCB (5–18 when counting from the left) that are underlined with a long black arrow were inverted in their arrangement in strain NADC 6564 compared to the other strains included in this comparison. The LCB 18 and 19 that are underlined with a shorter black arrow had inverse orientation in Sakai compared to the orientation of these two LCB in other strains. Chromosomal sequences were aligned using Mauve